Predicting carcass composition of young bulls

Recent genetic evaluations tend to use ultrasound measurements on young seedstock cattle primarily yearling bulls rather than carcass measurements from commercial progeny. However, some have questioned the validity of using ultrasound data in seedstock selection programs. In a University of Guelph study, pre-slaughter ultrasound and carcass dissection data from 47 crossbred yearling bulls were used

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Recent genetic evaluations tend to use ultrasound measurements on young seedstock cattle — primarily yearling bulls — rather than carcass measurements from commercial progeny. However, some have questioned the validity of using ultrasound data in seedstock selection programs.

In a University of Guelph study, pre-slaughter ultrasound and carcass dissection data from 47 crossbred yearling bulls were used to evaluate the following: 1) the value of six previously published equations based on live animal measurements; 2) the value of alternative pre-slaughter ultrasound measurements; and 3) the value of a short probe (127 mm) vs. a long probe (172 mm) to predict carcass lean meat yield. Following is a brief summary of results.

Prediction equations based on live animal measurements may provide more precise predictions of lean meat yield than equations derived from carcass measurements.

Supplementing ultrasonic backfat and ribeye muscle measurements with additional ultrasound measurements did not improve the accuracy or precision of lean meat yield prediction.

Lean meat yield of yearling bulls can be accurately predicted using backfat and ribeye muscle depth measurements with a short probe.

Of particular interest is the finding that the short probe may be as accurate as the long probe. The authors concluded this approach could significantly reduce the cost of collecting estimates of carcass composition in live seedstock without sacrificing accuracy or precision (Bergen et al. 2005. Can. J. Anim. Sci. 85:23). — Rick Rasby, University of Nebraska professor of animal science

Most calves are weaned by abrupt separation from their mamas. The responses are predictable — vocalizing, spending more time walking and less time eating and resting.

A method under study of weaning cattle in two stages may decrease behavioral disruptions, say researchers at the University of Saskatchewan's Western College of Veterinary Medicine. Stage 1 is preventing nursing between mother and calf before Stage 2 — separation of mother and calf, commonly known as fence-line weaning. Providing fence-line contact where mother and calf can see and hear each other decreases vocalizing and walking time.

Four trials explored the advantages to two-stage vs. traditional weaning. Calf weights and behaviors were recorded before and after pair separation.

Following separation, calves weaned in two stages vocalized 96.6% less and spent 78.9% less time walking, 23% more time eating and 24.1% more time resting than control calves.

Compared with controls, two-stage calves had lower average daily gain (ADG) when nursing was deprived, but greater ADG during the seven days following separation. In Trial 3, two-stage calves had greater growth rates than controls for seven weeks after separation, but no ADG effects were measured in Trials 1 and 2.

Researchers found calves weaned in two stages were less distressed than calves weaned by abrupt separation, but overall ADG didn't differ. The researchers attribute this to poor pasture conditions that may have decreased ADG by calves weaned in the two-stage method. — Haley et al. 2005. J. Anim. Sci. 83:2205-2214.

A three-year, Oregon State University study found infrequent supplementation of crude protein (CP) to cows on low-quality forage (<6% CP) can result in performance and grazing behavior similar to that of cows receiving supplement daily.

The researchers concluded that infrequent protein supplementation is an alternative that can lower labor and feed costs associated with supplementing cows grazing native range.

At the Northern Great Basin Experimental Range in southeast Oregon, 120 pregnant Angus × Hereford cows were allotted to three treatments: 1) unsupplemented control (CON); 2) supplementing every day (2 lbs. dry matter (DM)/cow) and 3) supplementation once every six days (12 lbs. DM/cow).

Cows were grazed for 84 days (August to November) each of three years. Cottonseed meal (43% CP) was the supplement.

Researchers found bodyweight and body condition scores were greater for supplemented cows compared with CON, but there were no differences due to supplementation frequency. Grazing time was greater for CON than for supplemented cows, with no difference due to supplementation frequency. Distance traveled, cow distribution, DM intake and DM digestibility weren't affected by protein supplementation or supplementation frequency.

The key to infrequent supplementation is to maintain a healthy rumen. The type of supplement being fed is key, especially when delivering a week's amount on one day. High starch supplements fed in this manner would be a concern (Schauer et al. 2005. J. Anim. Sci. 83:1115). — Rick Rasby, University of Nebraska professor of animal science

Conducted on behalf of Pfizer Animal Health, the analysis included data collected from 1995-2004 on more than 2.7 million calves. Researchers compared the price paid for calves in value-added health programs to that for similar calves unweaned and unvaccinated.

The analysis demonstrates calves in VAC 45 programs received premiums averaging $4.37/cwt. over the 10-year period. The premiums ranged from $2.47/cwt. in 1995 to a high of $7.91/cwt. in 2004. What's more, the price advantage for calves in VAC 45 programs has more than doubled in the last five years.

Meanwhile, calves in VAC 34 programs received premiums averaging $1.91/cwt. over the 10-year period, up to $3.47/cwt.

SLA reports more than a six-fold increase in the percentage of lots enrolled in VAC 45 programs and a three-fold increase in the percentage of lots taking part in VAC 34 programs from 1995-2004. — Colorado State University release

Eastern gamagrass loves heat, according to Agricultural Research Service (ARS) scientists at the ARS Henry A. Wallace Beltsville (MD) Agricultural Research Center. As temperatures increase, the better eastern gamagrass grows, the scientists say.

As the weather gets hotter, the plants produce higher yields, and store more carbon — which helps mitigate the effect on carbon dioxide (CO2) levels associated with global warming.

Simulating global warming conditions in outdoor climate-controlled chambers, researchers tested the plants at the current level of atmospheric CO2 — 370 ppm — as well as at double the amount — the level expected around 2100.

The experiments conducted with eastern gamagrass showed that when temperatures were increased from 68° F during the day and 57° F at night, to 95° F during the day and 84° F at night, the grass triples its carbon storage.

Eastern gamagrass is often referred to as “queen of the grasses.” It's a hardy, warm-season grass that grows well in marginal soils, and has been shown to even improve them.

Eastern gamagrass also seems to withstand hot, dry conditions. During the summer and early fall, when cool-season grasses are dormant, it provides a high-yielding forage is as nutritious as alfalfa, according to ARS. It also may have potential for use in conservation plantings. — ARS news release